1. Field of the Invention
The present invention relates to nitride semiconductor devices that are used in light emitting diodes (LEDs).
2. Description of the Related Art
In general, nitride semiconductor devices have been widely used in green or blue light emitting diodes (LEDs) or laser diodes (LDs) that are provided as light sources in full color displays, image scanners, various kinds of signal systems, and optical communication devices. The nitride semiconductor device can be provided as a light emitting device having an active layer that emits light of various colors including blue and green by recombination of electrons and holes.
Since the development of the nitride semiconductor devices, the technological advancements have been made to expand the utilization of the nitride semiconductor devices. Research has also been made on the nitride semiconductor devices as general lighting and vehicle light source. Particularly, in the related art, the nitride semiconductor device has been used as a component that is applied to a low power, low current mobile product. Recently, the use of the nitride semiconductor device has been gradually expanded to high power high current products.
FIG. 1 is a cross-sectional view illustrating a general nitride semiconductor device. Referring to FIG. 1, a general nitride semiconductor layer 10 includes a substrate 11, an n-type nitride semiconductor layer 12, an active layer 13, and a p-type nitride semiconductor layer 15. An electronic blocking layer 14 is formed between the active layer 13 and the p-type nitride semiconductor layer 15. A p-type electrode 16b is formed on an upper surface of the mesa-etched p-type nitride semiconductor layer 15. An n-type electrode 16a is formed on an upper surface of the exposed n-type nitride semiconductor layer 12. The electron blocking layer 14 prevents electrons having higher mobility than holes from overflowing into the p-type nitride semiconductor layer 15, thereby increasing recombination efficiency of the electrons and carriers within the active layer 13. The electron blocking layer 14 can also serve as a barrier against the holes as well as the electrons. Therefore, the concentration of the holes passing the electron blocking layer 14 and entering the active layer 13 is reduced to increase an operating voltage.